Roof cleaning is the process of removing algae, [1] mold, mildew, lichen and moss from roofs. [2] Also cleaning oxidation on metal roofs. Cleaning can extend the duration of a roof's ability to function. [2] Algae and other types of build-up often form on the north and west parts of roofs that are shaded or receive less sun, and can reduce a roof's life expectancy. [2] The presence of soot, dirt, or biomass can affect how much sunlight is absorbed by a roof and thus the amount of heat a building absorbs. [3]
Cleaning may be accomplished with a bleach or sodium percarbonate solution, [4] various cleaning products or commercial cleaning services. The Asphalt Roofing Manufacturers Association (ARMA) recommends using a 50/50 solution of household strength sodium hypochlorite (pool chlorine) and water to remove moss and algae. [5] The addition of zinc strips near the roof's peak may reduce the regrowth of algae and moss. Zinc sulfate can also be applied on an annual basis.
One safe and effective means to clean a roof is an electric agricultural sprayer system, as originally developed in Florida, USA in the early 1990s. [6] The equipment is used to apply a cleaning solution (typically containing bleach) that kills the algae, bacteria, mold, mildew, moss, fungus and other organic organisms growing on the roof. This process is referred to as soft washing. The equipment does not use pressure or mechanical means to clean the roof. Using a pressure washer, or any other gas powered device, to clean a roof at more than 100 PSI can damage the roof. The U.S. based Asphalt Roofing Manufacturers' Association specifies the use of a bleach cleaning solution, without the use of a pressure washer, to remove algae from a roof. ARMA discourages the use of a pressure washer, a flat-surface cleaner or any other mechanical device to clean a roof. Safe, effective soft washing cannot be achieved with a pressure washer, as the Venturi device (downstreaming) cannot achieve sufficient strength of solution to kill the organisms, cleaning the roof. Use of different tips on the pressure washer, so that it drops the pressure down to around 500 psi (3,400 kPa) or less, relies on the pressure of the equipment, and not the chemicals, to clean the roof.
Never use a pressure washer as this may damage the roof. [7] Roof cleaning devices exist that may minimize the spread of airborne radioactive materials (in contaminated areas) and other harmful materials, such as asbestos. [8] Specialized robots have been designed to facilitate cleaning roofs. [9]
Sodium hypochlorite is an alkaline inorganic chemical compound with the formula NaOCl. It is commonly known in a dilute aqueous solution as bleach or chlorine bleach. It is the sodium salt of hypochlorous acid, consisting of sodium cations and hypochlorite anions.
Trisodium phosphate (TSP) is an inorganic compound with the chemical formula Na3PO4. It is a white, granular or crystalline solid, highly soluble in water, producing an alkaline solution. TSP is used as a cleaning agent, builder, lubricant, food additive, stain remover, and degreaser.
Sodium percarbonate, or sodium carbonate peroxide is a chemical substance with formula Na
2H
3CO
6. It is an adduct of sodium carbonate and hydrogen peroxide whose formula is more properly written as 2 Na
2CO
3 · 3 H
2O
2. It is a colorless, crystalline, hygroscopic and water-soluble solid. It is sometimes abbreviated as SPC. It contains 32.5% by weight of hydrogen peroxide.
In chemistry, hypochlorite, or chloroxide is an anion with the chemical formula ClO−. It combines with a number of cations to form hypochlorite salts. Common examples include sodium hypochlorite and calcium hypochlorite. The Cl-O distance in ClO− is 1.69 Å.
A flat roof is a roof which is almost level in contrast to the many types of sloped roofs. The slope of a roof is properly known as its pitch and flat roofs have up to approximately 10°. Flat roofs are an ancient form mostly used in arid climates and allow the roof space to be used as a living space or a living roof. Flat roofs, or "low-slope" roofs, are also commonly found on commercial buildings throughout the world. The U.S.-based National Roofing Contractors Association defines a low-slope roof as having a slope of 3 in 12 (1:4) or less.
Percent active chlorine is a unit of concentration used for hypochlorite-based bleaches. One gram of a 100% active chlorine bleach has the quantitative bleaching capacity as one gram of free chlorine. The term "active chlorine" is used because most commercial bleaches also contain chlorine in the form of chloride ions, which have no bleaching properties.
Pressure washing or power washing is the use of high-pressure water spray to remove loose paint, mold, grime, dust, mud, and dirt from surfaces and objects such as buildings, vehicles and concrete surfaces. The volume of a mechanical pressure washer is expressed in gallons or liters per minute, often designed into the pump and not variable. The pressure, expressed in pounds per square inch, pascals, or bar, is designed into the pump but can be varied by adjusting the unloader valve or using specialized nozzle tips. Machines that produce pressures from 750 to 30,000 psi or more are available.
Sodium perborate is chemical compound whose chemical formula may be written NaH2BO4, Na2H4B2O8, or, more properly, [Na+]2[B2O4(OH)4]2−. Its name is sometimes abbreviated as PBS.
An asphalt shingle is a type of wall or roof shingle that uses asphalt for waterproofing. It is one of the most widely used roofing covers in North America because it has a relatively inexpensive up-front cost and is fairly simple to install.
Portable water purification devices are self-contained, easily transported units used to purify water from untreated sources for drinking purposes. Their main function is to eliminate pathogens, and often also of suspended solids and some unpalatable or toxic compounds.
In chemical engineering, biochemical engineering and protein purification, cross-flow filtration is a type of filtration. Cross-flow filtration is different from dead-end filtration in which the feed is passed through a membrane or bed, the solids being trapped in the filter and the filtrate being released at the other end. Cross-flow filtration gets its name because the majority of the feed flow travels tangentially across the surface of the filter, rather than into the filter. The principal advantage of this is that the filter cake is substantially washed away during the filtration process, increasing the length of time that a filter unit can be operational. It can be a continuous process, unlike batch-wise dead-end filtration.
A roof coating is a monolithic, fully adhered, fluid applied roofing membrane. Many roof coatings are elastomeric, that is, they have elastic properties that allow them to stretch and return to their original shape without damage.
Bleach is the generic name for any chemical product that is used industrially or domestically to remove colour (whitening) from fabric or fiber or to disinfect after cleaning. It often refers specifically to a dilute solution of sodium hypochlorite, also called "liquid bleach".
Cleaning agents or hard-surface cleaners are substances used to remove dirt, including dust, stains, foul odors, and clutter on surfaces. Purposes of cleaning agents include health, beauty, removing offensive odor, and avoiding the spread of dirt and contaminants to oneself and others. Some cleaning agents can kill bacteria and clean at the same time. Others, called degreasers, contain organic solvents to help dissolve oils and fats.
Gloeocapsa magma is a species of bacteria in the gloeocapsa genus of cyanobacteria, an ancient line of photosynthesizing bacteria, which photolyze water generating oxygen gas. Ancient cyanobacteria were ancestral to the chloroplasts of all plants on earth. Gloeocapsa magma may resemble "algae" in that they are green, but in fact cyanobacteria are bacteria whereas algae are single-celled eukaryotes that are closely related to plants.
A denture cleaner is used to clean dentures when they are out of the mouth. The main use is to control the growth of microorganisms on the dentures, especially Candida albicans, thereby preventing denture-related stomatitis. When dentures are worn in the mouth, a biofilm develops which may be similar to dental plaque. It may become hardened and mineralized as dental calculus. Denture cleansers are also used to remove stains and other debris that may be caused by diet, tobacco use, drinking coffee, drinking tea, etc.
Water chlorination is the process of adding chlorine or chlorine compounds such as sodium hypochlorite to water. This method is used to kill bacteria, viruses and other microbes in water. In particular, chlorination is used to prevent the spread of waterborne diseases such as cholera, dysentery, and typhoid.
Bleach activators are compounds that allow a lower washing temperature than would be required otherwise to achieve the full activity of bleaching agents in the wash liquor. Bleaching agents, usually peroxides, are usually sufficiently active only at 60 °C and up. With bleach activators, this activity can be achieved at lower temperatures. Bleach activators are included in some laundry detergent powders, some laundry additive powders, and a few laundry additive pods. They are not included in any liquid laundry detergents. Bleach activators react with hydrogen peroxide in aqueous solution to form peroxy acids. Peroxy acids are more active bleaches than hydrogen peroxide at lower temperatures (<60 °C), but are too unstable to be stored in their active form, and hence must be generated in situ.
Chlorine-releasing compounds, also known as chlorine base compounds, is jargon to describe certain chlorine-containing substances that are used as disinfectants and bleaches. They include the following chemicals: sodium hypochlorite, chloramine, halazone, and sodium dichloroisocyanurate. They are widely used to disinfect water and medical equipment, and surface areas as well as bleaching materials such as cloth. The presence of organic matter can make them less effective as disinfectants. They come as a liquid solution, or as a powder that is mixed with water before use.
Soft washing is a cleaning method using low pressure water. More recently, the term "softwashing" has been used to describe any form of spraying chemicals at buildings where solutions are used to remove mildew, bacteria, algae and other organic stains from roofs and other building exteriors.
{{cite web}}
: CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link)